1. Field of the Invention
This invention relates to hazard spill suppressant and fire retardant delivery systems having equipment useful for quickly supplying and directing a suppressing mixture directly on a hazardous spill or a flaming area. The invention also relates to any equipment for producing a sprayable foam and to foam delivery systems. The form of the present invention primarily addresses airborne delivery of foam hazardous spill suppressants and foam fire retardants using a helicopter for a delivery platform.
2. Description of the Prior Art
The somewhat limited lifting capacity of the average helicopter has in the past prevented it from receiving widespread acceptance as an effective platform for applying a suppressing mixture to a chemical spill and as effective fire-fighting equipment. Only recently has the use of expandable foams been approved for forestry type fire suppression. This approval has enabled the helicopter to become not only effective, but economically competitive with large fixed wing fire bombers for fire fighting. The advantages of applying foam suppressants to chemical spill areas from the safety of the cabin closure of a helicopter with oxygen masks available can also now be realized.
Until now foam delivery equipment having a useful capacity and of a design compatible with helicopters has not been available. Liquid retardant delivery devices seen in past art patents are mostly designed for fixed wing aircraft or for heavy duty helicopters such as the Sikorsky S64F and for crane types having double rotors. Most tank systems designed for helicopters require frequent recharging and those systems seen in past art patents providing a foam mixture use rotor downwash to produce the foam. Some systems use rotor downwash to distribute foam retardant directly under the helicopter, very dangerous and unapproved for fire fighting.
To examine past art patents for airborne delivery of retardants showing methods and apparatus, especially delivery by helicopter, a patent search was conducted in the classes and subclasses 339/171.
Disclosures seen in the following patents, if not necessarily pertinent to my invention, provide a cross-section of available equipment and fire retardant delivery systems.
In a patent, U.S. Pat. No. 3,220,482, issued to K. A. Eveleth, Nov. 3, 1965, an early water tank system for use on a helicopter is shown. The tanks are cumbersome, the spray nuzzle is held and directed manually by a passenger, and the downwash of the rotor disburses the spray.
W. O. Andrews, in U.S. Pat. No. 3,273,651, dated Sept. 20, 1966, shows a large water tank with hoses to be lifted and delivered to a fire area by a heavy duty large double bladed helicopter.
U.S. Pat. No. 3,494,423, granted R. S. Stansbury et al on Feb. 10, 1970, illustrates a boom and nozzle attached at the front of a helicopter for spraying a premixed fire retardant liquid. The fire retardant liquid described as commercially available is passed through screens in the nozzle to produce a foam-like discharge which is disbursed by rotor down draft.
The A. Linkewich patent, U.S. Pat. No. 3,754,601, dated Aug. 28, 1973, describes double tanking where a measured amount of retardant material is mixed with water. His system is primarily designed for fire bombing by winged aircraft. This is a water-retardant mix which does not produce a foam.
Other patents of interest included Waldrum, U.S. Pat. No. 3,920,184, helicopter hydraulic planting; Barlow, U.S. Pat. No. 3,936,018, a helicopter agricultural sprayer; Tomlinson, U.S. Pat. No. 4,090,567, a crane-type fire fighting helicopter; Kurtgis, U.S. Pat. No. 4,477,289, washing high voltage insulators by helicopter; and Stevens, U.S. Pat. No. 4,589,614, a pick up tank under a helicopter for aerial burning and fire control.
In the past art patents examined, no methods and apparatus were seen capable of quick-mixing water, a retardant, and a liquified gas to provide an expanding foam that can be directed from a helicopter to a precise location well beyond the effects of the rotor wash. Rotor downwash distribution, seen in many past art patents, is not acceptable to fire fighting agencies because of the hazardous effect created by rotor downwash. Rotor downwash can restart a controlled fire, expand a going fire, distribute burning embers, and create a real danger to fire fighters on the ground. In chemical spills, rotor downwash might tend to widen the spill area and greatly increase the danger from chemical cloud distribution.